1. Technical Field
The present invention relates to a lifter.
2. Related Art
Japanese Patent Application Publication No. JP-A-2012-2115 discloses a lifter which is a roller lifter for use with internal combustion engines such as automobile engines. The disclosed lifter includes a lifter body and a roller which is caused to abut against an outer periphery of a cam thereby to be pressed. The lifter body includes a cylindrical part having an outer periphery slidable on an inner wall of a cylinder and a pair of supports axially protruding from one axial end of the cylindrical part. The roller is rotatably mounted on a support pin extending through both supports.
The cylindrical part has a rotation stopper formed to protrude outward on the one axial end of the cylindrical part, which end is located at the same side as the side where the supports for the roller are located. The rotation stopper prevents the lifter body from being rotated relative to the cylinder. The rotation stopper is slidably fitted in a rotation stopper groove formed along an inner wall of the cylinder.
In the lifter of the above-described type, a predetermined gap is defined between an outer periphery of the cylindrical part of the lifter body and the inner wall of the cylinder in order to guarantee smooth reciprocation of the lifter body. The lifter body would possibly be inclined relative to the inner wall of the cylinder when pressed by the cam in a range of the gap. If the lifter body is inclined, diagonal corners of the cylindrical part come into uneven contact with the inner wall of the cylinder (cocking). As a result, there would be a possibility of sliding wear of the inner wall of the cylinder in addition to occurrence of noise.
In view of the above-described problem, if the cylindrical part is supposedly extended to the one axial end side so that a guide length (a sliding region) of the cylindrical part is increased, the posture of the cylindrical part would be corrected with the result that cocking could be reduced. In this case, however, since the rotation stopper is located at the one axial end of the cylindrical part, the rotation stopper needs to be set not to enter a rotation trajectory of the cam. This limits the freedom in the design of the lifter to a large degree.